LAUSR

By April 2016, 22 out of the 24 citrus-producing states in Mexico had confirmed the presence of ‘Candidatus Liberibacter asiaticus’ (C. Las) in citrus trees and in the vector Diaphorina citri. The dissemination of C. Las in space and time is the result of a complex interaction between the host, the associated pathogen, the vector and the environment. During 22 months (July 2012–April 2014), the seasonal variation of C. Las in D. citri populations was determined by real-time polymerase chain reaction (PCR) in lime orchards at six locations in two municipalities in the state of Colima, Mexico. Results showed that the proportion of positive psyllids was very high throughout the year (overall incidence of 58.2%) with seasonal variability in the proportion of positive adults, whereby winter and spring have the highest levels. These periods mark the co-occurrence of a high density of potentially infective psyllids on a susceptible host with continual generation of new shoots, and optimal environmental conditions in the Pacific region.